JP2024074898A - Traffic light control device and traffic light - Google Patents

Abstract

To provide a traffic light control device capable of appropriately switching a display state of a signal display section even in a case where a control signal for switching the display state of the signal display section cannot be received.SOLUTION: A traffic light control device for controlling a traffic light comprises: an imaging section which picks up an image in the vicinity of an intersection; an acquisition section which wirelessly acquires information including time information indicating a time; and a display control section which identifies a reference time to be a reference based on the time information included in the information acquired by the acquisition section and switches a display state of a signal display section mounted in the traffic light based on the lapse of time from the identified reference time. On the basis of the image which is picked up by the imaging section, the display control section adjusts switch timing of the display state of the signal display section.SELECTED DRAWING: Figure 1

Description

The present invention relates to a traffic light control device and a traffic light.

Conventionally, traffic lights receive a control signal for switching the display state of the signal display unit from a higher-level control device, and switch the display state of the signal display unit based on this received control signal (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 10-97696

An aspect of the present invention is a traffic light control device that controls a traffic light, and includes an imaging unit that captures an image near an intersection, an acquisition unit that wirelessly acquires information including time information indicating the time, and a display control unit that identifies a reference time based on the time information included in the information acquired by the acquisition unit, and switches the display state of a signal display unit attached to the traffic light based on the elapsed time from the identified reference time, and the display control unit adjusts the timing of switching the display state of the signal display unit based on the image captured by the imaging unit.

Another aspect of the present invention is a traffic light equipped with the traffic light control device described above.

1 is a block diagram showing the configuration of a signal system and a signal control device according to an embodiment of the present invention. FIG. 2 is a state transition diagram illustrating transitions between traffic light modes. FIG. 2 is an explanatory diagram showing an example of an intersection (first example). FIG. 4 is an explanatory diagram showing an example of detected traffic volume. FIG. 2 is an explanatory diagram showing an example of periods during which a signal lamp is turned on and off. 4 is an operational diagram showing the operation of a traffic light in the present embodiment. FIG. FIG. 11 is an explanatory diagram showing an example of an intersection (second example).

It has been found that with the traffic light shown in Patent Document 1 mentioned above, if a control signal cannot be received from a higher-level control device, for example during a disaster, the display state of the signal display unit cannot be appropriately switched.
Therefore, aspects of the present invention provide a traffic light control device, a traffic light, and a program that can appropriately switch the display state of a signal display unit even when a control signal for switching the display state of the signal display unit cannot be received.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic block diagram showing the configuration of a signal system 1 according to an embodiment of the present invention. In the signal system 1, a signal control device 100 provided in each of a plurality of signals is connected to a host control device 200 via a communication network 300. Hereinafter, the signal control device 100 will be described as a signal 100.

In this description, it is assumed that multiple traffic lights 100 are installed on a road and each is identified by identification information. The host control device 200 transmits control signals for controlling each of the traffic lights 100 to the traffic lights 100 via the communication network 300. This allows the host control device 200 to control each of the multiple traffic lights 100.

The multiple traffic lights 100 each have the same configuration. Here, the configuration of one traffic light 100 will be described. The traffic light 100 has an imaging unit 10, a control unit 20, a signal display unit 30, a power supply unit 40, and a sound collection unit 50. The imaging unit 10 and the control unit 20 are connected via an I/F (interface) 70. The control unit 20 and the signal display unit 30 are connected via an I/F 71. The sound collection unit 50 and the control unit 20 are connected via an I/F (interface) 72.

The signal display unit 30 comprises a first light-emitting unit 31, a second light-emitting unit 32, and a third light-emitting unit 33. The first light-emitting unit 31 lights up blue (or green), and when lit indicates that "you may proceed" (hereinafter referred to as "you may proceed"). The second light-emitting unit 32 lights up yellow, and when lit indicates that "you must stop at the stop position. However, if you are unable to stop at the stop position, you may proceed" (hereinafter referred to as "stop"). The third light-emitting unit 33 lights up red, and when lit indicates that "you may not proceed" (hereinafter referred to as "you may not proceed").

The imaging unit 10 includes an imaging device such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and outputs the captured image to the control unit 20 via the I/F 70. The imaging unit 10 is attached to the traffic light 100. For example, the imaging unit 10 is attached to the traffic light 100 so that it is located above, below, to the left, or to the right of the signal display unit 30. The imaging unit 10 may also be attached to the traffic light 100 as an integral part of the signal display unit 30.

As an example, the imaging unit 10 captures images in a 360-degree azimuth in the horizontal direction. In this case, the imaging unit 10 may capture images in a 360-degree azimuth by combining multiple imaging devices. The imaging unit 10 may also capture images in a 360-degree azimuth by processing images captured through a mirror member in the shape of a triangular pyramid or sphere.

The sound collection unit 50 is a sound collection device such as a microphone, and outputs the collected sound to the control unit 20 via the I/F (interface) 72. For example, the sound collection unit 50 may be a sound collection device equipped with multiple microphones that collects sound so that the direction of the sound source can be identified. The sound collection unit 50 is attached to the traffic light 100. For example, the sound collection unit 50 is attached to the traffic light 100 so that it is located above, below, to the left, or to the right of the signal display unit 30. The sound collection unit 50 may also be attached to the traffic light 100 as an integral part of the signal display unit 30.

The power supply unit 40 supplies power to the imaging unit 10, the control unit 20, the signal display unit 30, and the sound collection unit 50, which are the components of the traffic light 100.

The power supply unit 40 includes a power supply unit 41, a power storage unit 42, and a power supply switching unit 43. Power is supplied to the power supply unit 41 from outside the traffic light 100 via a power line. The power storage unit 42 accumulates power (charge) and outputs the accumulated power. For example, the power storage unit 42 is charged by the power supplied to the power supply unit 41 during the period when power is supplied to the power supply unit 41 from the outside. The power storage unit 42 is, for example, a secondary battery.

The power supply switching unit 43 supplies power from, for example, either the power supply unit 41 or the power storage unit 42 to each component of the traffic light 100. This power supply switching unit 43 detects the voltage or current of the power supply supplied to the power supply unit 41, and switches the power supply unit 41 that supplies power to each component of the traffic light 100 between the power supply unit 41 and the power storage unit 42 based on the detected voltage or current.

Now, the switching of modes by the power supply switching unit 43 will be described with reference to FIG. 2. In the following description, the case where the power supply switching unit 43 supplies power from the power supply unit 41 to each component of the traffic light 100 will be referred to as the "first mode," and the case where the power supply switching unit 43 supplies power from the power storage unit 42 to each component of the traffic light 100 will be referred to as the "second mode."

First, when the traffic light 100 is started (in FIG. 2, in the case of the "start-up" state), the power supply switching unit 43 transitions the state to the first mode if startup condition 1 is satisfied, and transitions the state to the second mode if startup condition 2 is satisfied.

This startup condition 1 may be, for example, a condition in which the voltage or current of the power source supplied to the power supply unit 41 is greater than a predetermined threshold. Also, this startup condition 2 may be, for example, a condition in which the voltage or current of the power source supplied to the power supply unit 41 is equal to or less than a predetermined threshold. In other words, startup condition 1 may be a condition in which power is supplied to the traffic light 100 from an external source, and startup condition 2 may be a condition in which power is not supplied to the traffic light 100 from an external source.

After that, for example, when the power supply unit 41 supplies power to each component of the traffic light 100 (when the state is in the first mode), the power supply switching unit 43 detects the voltage or current of the power supplied to the power supply unit 41. Then, when the detected voltage or current becomes equal to or lower than a predetermined threshold (when condition 2 is satisfied), the power supply switching unit 43 switches the power supply to the power storage unit 42 (transitions the state to the second mode).

Condition 2 corresponds to, for example, a case in which the power line supplying power to the traffic light 100 is cut or a power outage occurs in the facility supplying power to the traffic light 100 during a disaster or the like.

When power is being supplied from the power storage unit 42 to each component of the traffic light 100 (when the state is in the second mode), the power source switching unit 43 detects the voltage or current of the power source supplied to the power source unit 41. When the detected voltage or current becomes greater than a predetermined threshold (when condition 1 is satisfied), the power source switching unit 43 switches the power source to the power source unit 41 (transitions the state to the first mode).

Condition 1 corresponds, for example, to a case where a disconnected power line supplying power to the traffic light 100 is reconnected as a result of recovery processing after a disaster, or a case where a power outage at a facility supplying power to the traffic light 100 ends.

Then, the power supply switching unit 43 transitions the state between the first mode and the second mode. The power supply switching unit 43 outputs to the control unit 20 information indicating that the state is to transition from the first mode to the second mode, and information indicating that the state is to transition from the second mode to the first mode. Alternatively, the power supply switching unit 43 outputs to the control unit 20 information indicating that the current state is the first mode or the second mode. This information enables the control unit 20 to determine whether the current mode is the first mode or the second mode.

Returning to the explanation of FIG. 1, the control unit 20 includes a detection unit 21, a display control unit 22, and a communication unit 23. The communication unit 23 receives a control signal for switching the display state of the signal display unit 30 from the upper control device 200 via the communication network 300. This control signal is, for example, control information indicating whether proceeding is possible, whether to stop, or whether proceeding is not possible. In other words, this control signal is control information indicating that the first light-emitting unit 31, the second light-emitting unit 32, or the third light-emitting unit 33 should be illuminated.

In the first mode, the display control unit 22 switches the display state of the signal display unit 30 via the I/F 71 based on a control signal received from the upper control device 200 by the communication unit 23. For example, in the first mode, when the display control unit 22 receives control information from the upper control device 200 via the communication unit 23 indicating that the first light-emitting unit 31 is to emit light, the display control unit 22 turns on the first light-emitting unit 31 provided in the signal display unit 30 and turns off the second light-emitting unit 32 and the third light-emitting unit 33.

The detection unit 21 detects traffic volume based on the image captured by the imaging unit 10. In the second mode, the display control unit 22 switches the display state of the signal display unit 30 based on the traffic volume detected by the detection unit 21.

For example, the detection unit 21 detects the traffic volume of each of the multiple lanes based on the images of the multiple lanes captured by the imaging unit 10. At this time, as an example, the detection unit 21 detects vehicles one by one and for each lane in the images of the multiple lanes captured by the imaging unit 10 using image processing and pattern matching technology. Then, the detection unit 21 detects the traffic volume of each of the multiple lanes by detecting the number of vehicles traveling on each lane per unit time.

The display control unit 22 switches the display state of the signal display unit 30 based on the result of comparing the traffic volume of each of the multiple lanes detected by the detection unit 21. At this time, the display control unit 22 switches the display state of the signal display unit 30 based on the result of comparing the traffic volume of each of the multiple lanes detected by the detection unit 21 so that vehicles traveling on lanes with high traffic volume are given priority over vehicles traveling on lanes with low traffic volume.

In this way, in the first mode, the control unit 20 switches the display state of the signal display unit 30 attached to the traffic light 100 based on the control signal received from the higher-level control device 200 by the communication unit 23. In the second mode, the control unit 20 switches the display state of the signal display unit 30 attached to the traffic light 100 based on the image captured by the imaging unit 10.

Next, using Figures 3 to 5, an example will be described in which, in the second mode, the display control unit 22 switches the display state of the signal display unit 30 based on the traffic volume detected by the detection unit 21.

Here, we will explain the case of two one-way lanes, as shown in Figure 3. One of the two lanes, lane A, is a one-way lane that runs from right to left on the paper surface of Figure 3. The other of the two lanes, lane B, is a one-way lane that runs from top to bottom on the paper surface of Figure 3. Lane A and lane B intersect with each other at intersection C.

In addition, in FIG. 3, traffic light 100-1 is installed on lane A just before intersection C. Traffic light 100-2 is installed on lane B just before intersection C. Traffic lights 100-1 and 100-2 have the same configuration as traffic light 100 described above with reference to FIG. 1.

In addition, in FIG. 3, at intersection C, there is a stop line L1 before traffic light 100-1, and there is a stop line L2 before traffic light 100-2. Therefore, depending on the signal display units 30 of traffic lights 100-1 and 100-2, at intersection C, the vehicle stops before the stop line L1, and also before the stop line L2.

Next, the traffic volume detected by the traffic light 100 will be described using FIG. 4. Here, the traffic light display units 30 of the traffic lights 100-1 and 100-2 are described as each having a first light-emitting unit 31 that lights up blue (or green) to indicate that proceeding is permitted, and a third light-emitting unit 33 that lights up red to indicate that proceeding is prohibited.

Here, the control units 20 of the traffic lights 100-1 and 100-2 are described as causing the signal display units 30 of their own devices to turn off the first light-emitting unit 31 and turn on the third light-emitting unit 33 almost simultaneously. Conversely, the control units 20 of the traffic lights 100-1 and 100-2 are described as causing the signal display units 30 of their own devices to turn on the first light-emitting unit 31 and turn off the third light-emitting unit 33 almost simultaneously.

As described above, traffic lights 100-1 and 100-2 each capture images in a 360-degree horizontal direction. Therefore, traffic lights 100-1 and 100-2 can detect the traffic volume in lanes A and B, respectively.

Here, for example, as shown in FIG. 4, traffic lights 100-1 and 100-2 alternate between a display state of "Proceed" and a display state of "Proceed not allowed" via their respective signal display units 30. Here, the respective periods during which the display states of "Proceed" and "Proceed not allowed" are described as having the same length of time.

For example, in period T1, traffic light 100-1 indicates "Proceed" via its own signal display unit 30, and traffic light 100-2 indicates "Do not proceed" via its own signal display unit 30. Next, in period T2, traffic light 100-1 indicates "Do not proceed" via its own signal display unit 30, and traffic light 100-2 indicates "Proceed" via its own signal display unit 30. Thereafter, traffic lights 100-1 and 100-2 repeat the same operation for periods T3, T4, etc. It is assumed that periods T1, T2, T4, etc. are each the same length of time.

Here, the detection unit 21 of traffic light 100-1 detects the traffic volume of each of the multiple lanes based on the images of the multiple lanes captured by the imaging unit 10 of traffic light 100-1. Also, the detection unit 21 of traffic light 100-2 detects the traffic volume of each of the multiple lanes based on the images of the multiple lanes captured by the imaging unit 10 of traffic light 100-2.

For example, as shown in FIG. 4, the detection units 21 of traffic lights 100-1 and 100-2 each detect that five vehicles have passed through lane A and zero vehicles have passed through lane B during time period T1. Furthermore, the detection units 21 of traffic lights 100-1 and 100-2 each detect that zero vehicles have passed through lane A and one vehicle has passed through lane B during time period T2. Similarly, the detection units 21 of traffic lights 100-1 and 100-2 each detect the traffic volume of lane A and lane B during time periods T3, T4, and so on.

The display control unit 22 of traffic light 100-1 then compares the traffic volume of each of the multiple lanes detected by the detection unit 21 of traffic light 100-1, and in this case determines that lane A has a higher traffic volume than lane B. For example, the display control unit 22 of traffic light 100-1 may compare the traffic volume of each lane based on the total or average of the vehicles that have traveled on each lane during a predetermined period such as period T1 to period T4.

Then, based on this result, the display control unit 22 of the traffic light 100-1 switches the display state of the signal display unit 30 so that vehicles traveling on lanes with high traffic volume are given priority over vehicles traveling on lanes with low traffic volume. In other words, in this case, since lane A has more traffic volume than lane B, the display control unit 22 of the traffic light 100-1 switches the display state of the signal display unit 30 so that lane A is given priority over lane B.

Meanwhile, the display control unit 22 of traffic light 100-2 compares the traffic volume of each of the multiple lanes detected by the detection unit 21 of traffic light 100-2, and determines, in this case, that lane A has more traffic volume than lane B, just like the display control unit 22 of traffic light 100-1. Then, based on this result, the display control unit 22 of traffic light 100-2 switches the display state of the signal display unit 30 so that vehicles traveling in lanes with more traffic volume are given priority over vehicles traveling in lanes with less traffic volume. That is, in this case, because lane A has more traffic volume than lane B, the display control unit 22 of traffic light 100-2 switches the display state of the signal display unit 30 so that lane A is given priority over lane B, just like the display control unit 22 of traffic light 100-1.

Here, the physical quantity of traffic volume in multiple lanes will have the same value even if the measuring entity is different, such as traffic light 100-1 and traffic light 100-2, as long as the measuring period is the same. Therefore, the traffic volume values in multiple lanes detected by the detection unit 21 of traffic light 100-1 and the detection unit 21 of traffic light 100-2 will be the same value. Therefore, the display control unit 22 of traffic light 100-1 and the display control unit 22 of traffic light 100-2 can each switch the display state of the signal display unit 30 based on the traffic volume for each of the detected multiple lanes so that lane A is given priority over lane B. In this way, even if traffic light 100-1 and traffic light 100-2 operate independently of each other and even if they do not receive a control signal from a higher-level control device, they can appropriately switch the display state of the signal display unit 30 based on the detected traffic volume for each lane.

As an example, when switching the display state of the signal display unit 30 so that lane A is given priority over lane B, the display control unit 22 of traffic light 100-1 and the display control unit 22 of traffic light 100-2 each do the following:

For example, the display control units 22 of traffic lights 100-1 and 100-2 switch the display state of the signal display unit 30 based on the traffic volume for each of the multiple lanes detected by the detection unit 21 of the traffic light 100 itself, so that the greater the ratio or difference in traffic volume for each lane, the longer the period during which it is possible to proceed in lanes with a high traffic volume than in lanes with a low traffic volume.

Conversely, the display control units 22 of traffic lights 100-1 and 100-2 switch the display state of the signal display unit 30 based on the traffic volume for each of the multiple lanes detected by the detection unit 21 of their own traffic light 100, so that the greater the ratio or difference in traffic volume for each lane, the longer the period during which passage is not permitted for lanes with less traffic volume than for lanes with more traffic volume.

In the case of FIG. 4 described above, the display control units 22 of traffic lights 100-1 and 100-2 change the duration of the display state of the signal display unit 30, as shown in FIG. 5 as an example. For example, each display control unit 22 changes the duration of periods T11 and T13 during which the signal display unit 30 (lane A) of traffic light 100-1 indicates that proceeding is permitted and the signal display unit 30 (lane B) of traffic light 100-2 indicates that proceeding is prohibited, so that they are longer than the durations of periods T1 to T4 shown in FIG. 4.

Conversely, each display control unit 22 changes the time length between periods T12 and 14, during which the signal display unit 30 (lane A) of traffic light 100-1 indicates no proceeding and the signal display unit 30 (lane B) of traffic light 100-2 indicates proceeding, to be shorter than the time length in the case of periods T1 to T4 shown in FIG. 4. Thereafter, each display control unit 22 repeats switching the display state of each signal display unit 30 in the same manner as in the case of periods T11 to T14 until the traffic volume changes.

In this way, the display control unit 22 of the traffic light 100 can switch the display state of the signal display unit 30 based on the traffic volume for each of the multiple lanes detected by the detection unit 21 so that vehicles traveling in lanes with high traffic volume are given priority over vehicles traveling in lanes with low traffic volume.

<Operation of Traffic Light 100 When Transitioned to Second Mode>
Next, the operation of the traffic light 100 in the second mode will be described with reference to Fig. 6. Note that the operation of the traffic light 100 in Fig. 6 is, for example, the operation of the traffic light 100 when the traffic light transitions from the first mode to the second mode as described with reference to Fig. 2.

First, the imaging unit 10 captures an image and outputs the captured image to the control unit 20 via the I/F 70 (step S10). Next, the detection unit 21 of the control unit 20 detects the traffic volume based on the image captured by the imaging unit 10 (step S20). Next, the display control unit 22 of the control unit 20 compares the traffic volume of each of the multiple lanes detected by the detection unit 21 (step S30).

Next, the display control unit 22 of the control unit 20 performs signal control by switching the display state of the signal display unit 30 based on the result of the comparison in step S30 (step S40). For example, the display control unit 22 of the control unit 20 switches the display state of the signal display unit 30 based on the result of comparing the traffic volumes of each of the multiple lanes detected by the detection unit 21 in this step S40, so that vehicles traveling on lanes with high traffic volume are given priority over vehicles traveling on lanes with low traffic volume. In this step S40, the display control unit 22 of the control unit 20 switches the display state of the signal display unit 30 via the I/F 71.
Thereafter, the traffic light 100 repeats the process from step S10 until it transitions to the first mode.

In this way, in the second mode, the traffic light 100 switches the display state of the signal display unit 30 attached to the traffic light 100 based on the image captured by the imaging unit 10. Therefore, the traffic light 100 according to this embodiment can appropriately control the switching of the display state of the signal display unit 30 even when it is unable to communicate with a higher-level control device or when it is unable to receive a control signal from the higher-level control device.

As shown in FIG. 4 or FIG. 5, the control unit 20 of each traffic light 100 switches the display state of each traffic light display unit 30 so that the display state of traffic light 100-1 and the display state of traffic light 100-2 are different.

In the case of FIG. 3, in order to prevent a vehicle traveling in lane A and a vehicle traveling in lane B from colliding at intersection C, traffic lights 100-1 and 100-2 need to control the signal display unit 30 of each traffic light 100 by the control unit 20 of the traffic light 100 itself. For example, the control unit 20 of each traffic light 100 needs to control the signal display unit 30 of the traffic light 100 by the control unit 20 of the traffic light 100 itself so that a vehicle traveling in lane A and a vehicle traveling in lane B are not able to proceed toward intersection C at the same time.

In other words, the display state of the traffic signal 100-1 and the display state of the traffic signal 100-2 are not permitted to both be in a state in which proceeding is permitted at the same time. However, the display state of the traffic signal 100-1 and the display state of the traffic signal 100-2 are both permitted to be in a state in which proceeding is prohibited.
Therefore, the control unit 20 provided in each traffic light 100 switches the display state of each signal display unit 30 so that the display state of traffic light 100-1 and the display state of traffic light 100-2 are different and so that both are not in a display state that allows progress at the same time.
This allows a vehicle traveling on lane A and a vehicle traveling on lane B to proceed alternately through the intersection C without colliding with each other at the intersection C.

As explained above with reference to FIG. 4, even if the devices that measure traffic volume are different, such as traffic lights 100-1 and 100-2, it is necessary to ensure that the values of the physical quantity, i.e., traffic volume on multiple lanes, are measured as the same value by each device. To achieve this, the start and end times of periods T1, etc., during which the number of vehicles are measured, must be synchronized between traffic lights 100-1 and 100-2.

For this synchronization, traffic lights 100-1 and 100-2 may be able to detect each other's reference time, for example, by using a radio clock or a GPS (Global Positioning System) to keep time. Traffic lights 100-1 and 100-2 then measure the time that has elapsed since the detected reference time using their own internal timekeeping units. Traffic lights 100-1 and 100-2 then determine the start and end times of periods T1 and the like during which the number of vehicles are measured, based on the elapsed time measured by their respective timekeeping units. In this way, traffic lights 100-1 and 100-2 may synchronize the start and end times of periods T1 and the like during which the number of vehicles are measured between traffic lights 100-1 and 100-2.

As a result, even if traffic signals 100-1 and 100-2 use different devices to measure traffic volume, the values of the physical quantity of traffic volume on multiple lanes can be measured as the same value by each device. Therefore, traffic signals 100-1 and 100-2 can appropriately switch the display state of the signal display unit 30.

In the explanation of FIG. 4, traffic lights 100-1 and 100-2 compare the traffic volume of each of the multiple lanes when the period from period T1 to period T4 has elapsed, and switch the display state of the signal display unit 30 based on the comparison result. However, the timing for comparing the traffic volume of each of the multiple lanes is not limited to this. For example, traffic lights 100-1 and 100-2 may compare the traffic volume of each of the multiple lanes for each predetermined period.

This "predetermined period" may be any period that is determined in advance. In addition, this "predetermined period" may be determined based on the period during which the control unit 20 of each traffic light 100 switches the display state of the signal display unit 30, such as the above-mentioned periods T1 to T4.

The "predetermined period" may be any one of periods T1 to T4. For example, traffic lights 100-1 and 100-2 may each compare the number of moving vehicles in lane A and the number of stopped vehicles in lane B during period T1, and switch the display state of the signal display unit 30 based on the result of this comparison.

Furthermore, as in the case of period T1, traffic lights 100-1 and 100-2 each compare the number of traveling vehicles in lane A and the number of stopped vehicles in lane B for each period T2, T3, T4, etc. Then, based on the results of the comparison, traffic lights 100-1 and 100-2 may each switch the display state of the signal display unit 30 so that vehicles traveling in lanes with high traffic volume are given priority over vehicles traveling in lanes with low traffic volume.

In addition, traffic lights 100-1 and 100-2 may compare the traffic volume of each of the multiple lanes when the total number of vehicles traveling on the multiple lanes exceeds a predetermined number.

Although the traffic volume has been described here as the number of vehicles traveling in a lane or the number of vehicles traveling per unit time, the traffic volume is not limited to this. For example, the detection unit 21 may detect the number of vehicles stopped before intersection C, that is, the number of vehicles stopped for each lane, as the traffic volume. In this case, the display control unit 22 can switch the display state of the signal display unit 30 so as to reduce the number of stopped vehicles depending on the stopped vehicles.

<For multiple lanes>
In the explanation above using Figure 3, we have described the case of two lanes, each of which is one-way. However, the traffic light 100 of this embodiment is not limited to such a case of two one-way lanes, and can accommodate any number of lanes that are not one-way.

Here, we will use Figure 7 to explain an example of a road with any number of lanes that is not one-way. In this figure, parts that correspond to those in Figures 1 and 3 are given the same reference numerals, and their explanations will be omitted.

In FIG. 7, lanes A1 and A2, which are oncoming lanes, and lanes B1 and B2, which are oncoming lanes, intersect at intersection C. Traffic lights 100-1 and 100-3, and traffic lights 100-2 and 100-4 are installed on lanes A1 and A2, and on lanes B1 and B2, just before intersection C. Traffic lights 100-1, 100-2, 100-3, and 100-4 have the same configuration as traffic light 100 described using FIG. 1, just like in FIG. 3.

In addition, in FIG. 7, at intersection C, there is a stop line L1 just before traffic light 100-1, and a stop line L3 just before traffic light 100-3. At intersection C, there is a stop line L2 just before traffic light 100-2, and a stop line L4 just before traffic light 100-4. Therefore, depending on the signal display units 30 of traffic lights 100-1 to 100-4, vehicles in each lane will stop just before stop line L1 to stop line L4 at intersection C.

In the case of FIG. 7, as in the case of FIG. 3, traffic lights 100-1, 100-2, 100-3, and 100-4 need to have their signal display units 30 controlled by their own control units 20 so that a vehicle traveling in lane A1 or lane A2 does not collide with a vehicle traveling in lane B1 or lane B2 at intersection C.

For example, the control unit 20 of each traffic light 100 must control the signal display unit 30 of the traffic light 100 by the control unit 20 of the traffic light 100 itself so that a vehicle traveling in lane A1 or lane A2 and a vehicle traveling in lane B1 or lane B2 are not allowed to proceed toward intersection C at the same time.

Therefore, as an example, the control units 20 of traffic lights 100-1 and 100-3 each switch the display state of the signal display unit 30 at the same timing and to the same display state. Also, the control units 20 of traffic lights 100-2 and 100-4 each switch the display state of the signal display unit 30 at the same timing and to the same display state. Then, the control units 20 provided in each traffic light 100 switch the display state of each signal display unit 30 so that the display state of traffic lights 100-1 and 100-3 is different from the display state of traffic lights 100-2 and 100-4.

As explained above, the display state of traffic signals 100-1 and 100-3 and the display state of traffic signals 100-2 and 100-4 are not permitted to both be able to proceed at the same time. This is because if the display state of traffic signals 100-1 and 100-3 and the display state of traffic signals 100-2 and 100-4 both become unable to proceed at the same time, there is a possibility that vehicles traveling in different lanes may collide at intersection C. However, it is possible for the display state of traffic signals 100-1 and 100-3 and the display state of traffic signals 100-2 and 100-4 to both be unable to proceed.

Therefore, the control unit 20 provided in each traffic light 100 switches the display state of each traffic light display unit 30 so that the display state of traffic lights 100-1 and 100-3 is different from the display state of traffic lights 100-2 and 100-4, and so that both are not in a display state that allows proceeding at the same time.

Therefore, in this case too, the control units 20 of the traffic lights 100-1 and 100-3 switch the display state of the signal display unit 30 as in the case of lane A described in FIG. 4, and the control units 20 of the traffic lights 100-2 and 100-4 switch the display state of the signal display unit 30 as in the case of lane B described in FIG. 4. Therefore, in the case of FIG. 7 as in the case of FIG. 4, the traffic lights 100-1 to 100-4 can appropriately control the switching of the display state of the signal display unit even when they cannot communicate with the higher-level control device or when they cannot receive a control signal from the higher-level control device.

As shown by the symbol P in FIG. 7, there is a possibility that a vehicle may turn right from lane A1 at intersection C and travel on lane B2. In other words, there is a possibility that a vehicle may turn right at intersection C.

The display control unit 22 then switches the display state of the signal display unit 30 so as to prioritize right turns (right turn signal). This can reduce the increase in the number of vehicles unable to turn right, for example, when vehicles traveling on lane A1 are unable to turn right at intersection C and stop near stop line L1. Thus, the display control unit 22 can reduce (alleviate) congestion caused by turning right at intersection C.

The display control unit 22 also switches the display state of the signal display unit 30 so as to adjust the time of the right-turn signal. This makes it easier for vehicles to turn right at intersection C. This reduces the increase in the number of vehicles that are unable to turn right at intersection C and stop near the stop line L1. Thus, the display control unit 22 can reduce congestion caused by turning right at intersection C.

In this way, when the display control unit 22 switches the display state of the signal display unit 30 to prioritize right turns or to adjust the time of the right turn signal, the detection unit 21 detects vehicles turning right based on the captured image.

For example, based on the captured image, the detection unit 21 detects a vehicle that is stopped at or before the intersection C and is close to the right edge of the lane as a vehicle turning right. Also, assume that the image of the turn indicator equipped on the vehicle, which indicates the direction in which the vehicle will change lanes by blinking lights, is captured by the imaging unit 10. In this case, the detection unit 21 may detect a vehicle turning right by determining whether or not the vehicle is turning right based on the image of the turn indicator equipped on the vehicle captured by the imaging unit 10. Also, the detection unit 21 may detect a vehicle turning right by any combination of methods for detecting such vehicles turning right.

Then, as described above, when the detection unit 21 detects a vehicle turning right, the display control unit 22 switches the display state of the signal display unit 30 so as to prioritize the right turn or to adjust the time of the right turn signal.

When the display control unit 22 switches the display state of the signal display unit 30 to give priority to a right turn (right turn signal), this means that the display control unit 22 switches the display state of the signal display unit 30 so that vehicles turning right are given priority over vehicles that do not turn right or vehicles that do not turn right at intersection C. A "vehicle not turning right" here refers to, for example, a vehicle that travels straight in the lane without changing lanes, or a vehicle that turns left.

As an example, the signal display unit 30 is equipped with a light-emitting element that indicates that a right turn is permitted. In this case, the display control unit 22 controls the display state of the light-emitting element that indicates that a right turn is permitted, and switches the display state of the signal display unit 30 so that vehicles making a right turn have priority.

In addition, when the display control unit 22 switches the display state of the signal display unit 30 to adjust the time of the right-turn signal, this means that the display control unit 22 adjusts the time at which the display state of the signal display unit 30 is switched so that the period during which a vehicle turning right can proceed is longer compared to when there are no vehicles turning right at intersection C or when there are vehicles not turning right.

As an example, the signal display unit 30 is provided with a light-emitting unit corresponding to a right turn permitted. In this case, when the display control unit 22 switches the display state of the signal display unit 30 to adjust the time of the right turn signal, it means, for example, that the display control unit 22 controls the display state of the light-emitting unit corresponding to a right turn permitted and switches the display state of the signal display unit 30 so as to lengthen the period during which a vehicle turning right can turn right and proceed compared to a case in which there are no vehicles turning right at intersection C or compared to vehicles not turning right.

<Emergency vehicles have priority>
The detection unit 21 may detect the type of vehicle based on the captured image. For example, an emergency vehicle has red warning lights. Therefore, the detection unit 21 may determine whether or not the vehicle has red warning lights based on the captured image, and if the vehicle has red warning lights, detect the type of the vehicle as an emergency vehicle. The emergency vehicle is, for example, a fire engine, an ambulance, or a patrol car.

Emergency vehicles may also be a predetermined color, such as red or white. Thus, the detection unit 21 may determine whether the type of vehicle is an emergency vehicle by combining the color of the vehicle with the criterion of whether the vehicle has red warning lights. For example, the detection unit 21 may determine whether the color of the vehicle is red or white based on a captured image. Then, when the color of the vehicle is red or white and the vehicle has red warning lights, the detection unit 21 may detect the type of the vehicle as an emergency vehicle.

In the second mode, when the type of vehicle detected is an emergency vehicle, the display control unit 22 may switch the display state of the signal display unit 30 so that the emergency vehicle is given priority over vehicles that are not emergency vehicles. This allows the emergency vehicle to proceed through the lane with priority over vehicles that are not emergency vehicles. In this way, allowing emergency vehicles to proceed through the lane with priority is advantageous in times of disasters, etc.

When detecting the type of vehicle based on a captured image, the detection unit 21 may detect the type of vehicle based on the captured image and the sound collected by the sound collection unit 50. For example, if the type of vehicle is an emergency vehicle, the vehicle may be sounding a siren. The detection unit 21 may then determine whether the sound collected by the sound collection unit 50 includes the sound of a siren, and combine this determination result with the determination result based on the captured image described above to determine whether the type of vehicle is an emergency vehicle.

When the sound collection unit 50 is a sound collection device that collects sound so that the direction of the sound source can be identified, the detection unit 21 can detect the direction of an emergency vehicle equipped with a sound source that is sounding a siren. In this case, the detection unit 21 can more accurately detect the emergency vehicle based on the detected direction of the emergency vehicle and the direction of the emergency vehicle detected based on the image.

Since emergency vehicles can be detected more accurately in this way, the display control unit 22 can more accurately switch the display state of the signal display unit 30 in the second mode so that the emergency vehicle is given priority in proceeding. In addition, since the display control unit 22 can more accurately determine the direction of the emergency vehicle via the detection unit 21, it can also more accurately estimate the lane in which the emergency vehicle will proceed. Therefore, the display control unit 22 can switch the display state of the signal display unit 30 in the second mode so that the emergency vehicle is given priority in proceeding. In this way, emergency vehicles can proceed in the lane with priority. Being able to allow emergency vehicles to proceed in the lane with priority in this way is advantageous in times of disasters, etc.

<Measures against western and morning sun>
Incidentally, in the signal display unit 30 described above with reference to Fig. 1, each light-emitting unit corresponding to one signal may include a plurality of light-emitting elements. The light-emitting unit corresponding to one signal refers to the first light-emitting unit 31, the second light-emitting unit 32, or the third light-emitting unit 33 described above. Also, the plurality of light-emitting elements refers to a plurality of LEDs (Light Emitting Diodes), for example. That is, the signal display unit 30 of the traffic light 100 described above may be a light-emitting system using LEDs.

In this case, when the display control unit 22 of the control unit 20 turns on the light-emitting unit of the signal display unit 30, the display control unit 22 of the control unit 20 causes the multiple light-emitting elements included in the light-emitting unit to emit light such that some of the light-emitting elements emit light or turn off, and the location of the emitting or turning off light changes position in the light-emitting unit. In other words, the display control unit 22 of the control unit 20 causes the multiple light-emitting elements to emit light by moving only a portion of the lit areas (or turned-off areas), rather than lighting up all of the areas that can be lit for each color of the traffic light.

For example, when the setting sun or morning sun shines on the traffic light 100, a user looking at the traffic light 100 may find it difficult to visually determine which of the multiple light-emitting elements in the signal display unit 30 is emitting light. In contrast, when the display control unit 22 of the control unit 20 turns on the light-emitting elements of the signal display unit 30 as described above, the lit light-emitting elements do not simply remain lit, but the location where they are emitting light moves. Therefore, even when the setting sun or morning sun shines on the traffic light 100, a user looking at the traffic light 100 can easily visually determine which of the multiple light-emitting elements in the signal display unit 30 is emitting light.

When the display control unit 22 of the control unit 20 turns on the light-emitting unit of the signal display unit 30, the display control unit 22 may cause the light-emitting units to emit light such that some of the light-emitting units in the light-emitting unit emit light or turn off, and the emitting or turning off parts rotate, move, enlarge, or shrink in the light-emitting unit. In this way, even when the setting sun or morning sun shines on the traffic light 100, a user looking at the traffic light 100 can more easily see which of the light-emitting units in the signal display unit 30 are emitting light.

When the display control unit 22 of the control unit 20 lights up the light-emitting unit of the signal display unit 30, the display control unit 22 may change the brightness of the light-emitting element that is turned off and that is included in the light-emitting unit to make the light-emitting unit emit light. For example, when the display control unit 22 of the control unit 20 lights up the light-emitting unit of the signal display unit 30, while some of the light-emitting elements emit or turn off as described above, the brightness of the light-emitting elements that are turned off may be changed in sequence from dark to bright, rather than simply being left in an off state. Furthermore, the display control unit 22 of the control unit 20 may change the brightness of the light-emitting elements in sequence from dark to bright, and then from bright to dark, and repeat this change in brightness.

As a result, even if the setting sun or morning sun shines on the traffic light 100, a user looking at the traffic light 100 can more easily visually determine which of the multiple light-emitting elements in the signal display unit 30 is emitting light.

In the above description, the traffic lights 100 are described as operating independently of each other, but the traffic lights 100 may communicate with each other. For example, the traffic lights 100 may communicate with each other via the communication network 300 described with reference to FIG. 1. In the event of a disaster, communication via this communication network 300 may become impossible. Therefore, the traffic lights 100 may each communicate with each other via a communication network different from the communication network 300. In this case, the communication network may be a wireless communication network.

In the case of Fig. 3, such a communication network is sufficient if it can communicate at least between traffic lights 100-1 and 100-2 related to intersection C. In the case of Fig. 7, such a communication network is sufficient if it can communicate at least between traffic lights 100-1 to 100-4 related to intersection C.
3 or 7, each traffic light 100 switches the display state of each signal display unit 30 so that vehicles traveling in different lanes do not collide at intersection C. For example, the control unit 20 provided in each traffic light 100 switches the display state of each signal display unit 30 so that the display states of the traffic lights 100 corresponding to lanes that are not oncoming lanes are different and are not in a display state that allows progression at the same time.

If the traffic lights 100 related to the intersection are capable of communicating with each other in this way, they may transmit and receive information on detected traffic volume to each other. In this case, the imaging unit 10 in each traffic light 100 may be attached to the traffic light 100 so as to capture at least the lane for which traffic is controlled by the display state of the signal display unit 30. In other words, the traffic light 100 detects the traffic volume only for the lane for which it controls traffic. The detected traffic volume is then transmitted to the other traffic lights 100. In this way, all traffic lights 100 related to the intersection may detect the traffic volume of all lanes related to the intersection.

Even in this way, each traffic light 100 can detect the traffic volume for each lane based on the image captured by the imaging unit 10 of each traffic light. Therefore, as described using FIG. 3 or FIG. 7, this traffic light 100 can appropriately control the switching of the display state of the signal display unit even when it is unable to communicate with a higher-level control device or when it is unable to receive a control signal from the higher-level control device.

Note that, although the case where traffic lights 100 related to an intersection communicate with each other has been described here, the present invention is not limited to this. For example, traffic lights 100 installed in sequence on the same lane may communicate with each other. This allows each of the traffic lights 100 installed in sequence to control the signal display unit 30 of its own device so that vehicles traveling on the same lane and passing through the traffic lights 100 installed in sequence are not prevented from proceeding by any of the traffic lights 100 and are allowed to proceed.

When traffic signals 100 installed next to each other communicate with each other, the wireless communication unit of each traffic signal 100 may relay and forward the communication. This allows not only adjacent traffic signals 100 to communicate with each other, but also traffic signals 100 that are far apart to communicate with each other.

In the description of FIG. 2, the power supply switching unit 43 transitions between the first mode and the second mode based on the voltage or current of the power supply supplied to the power supply unit 41. However, this is not limited to the above, and the power supply switching unit 43 may transition between the first mode and the second mode based on a control signal for switching the mode. This control signal for switching the mode may be received, for example, via wireless communication. Furthermore, this control signal for switching the mode may be broadcast in the event of a disaster or the like. This allows each of the traffic lights 100 to reliably switch modes in the event of a disaster, without depending on the voltage or current of the power supply supplied to the power supply unit 41.

The traffic light 100 may be a temporary traffic light for construction work. In this case, the traffic light 100 may be operated by power supply only from the power storage unit 42. In this case, the traffic light 100 switches the display state of the signal display unit 30 attached to the traffic light 100 based on the image captured by the imaging unit 10. Therefore, a user can appropriately control the switching of the display state of the signal display unit 30 by simply installing the traffic light 100, which is a temporary traffic light for construction work, in a traffic lane, even if there is no communication between the upper control device 200 and the traffic light 100 and a control signal cannot be received from the upper control device 300. Therefore, the traffic light 100 can appropriately control traffic. Therefore, such a traffic light 100 is suitable for construction work.

When the traffic light 100 is a temporary traffic light for construction, the power supply unit 40 of the traffic light 100 may supply power to each component of the traffic light 100 only from the power storage unit 42. In this case, the power switching unit 43 may transition the state to the second mode after the power is turned on in the mode described using FIG. 2, and may continue to transition the state to the second mode thereafter.

For example, if the traffic light 100 is a temporary traffic light for construction work, it may not be supplied with power from the outside. As described above, the power supply unit 40 of the traffic light 100 supplies power to each component of the traffic light 100 only from the power storage unit 42, so that the control unit 22 can switch the display state of the signal display unit 30 even in this case where power is not supplied from the outside.

In the above description, as explained with reference to Figures 1 and 2, in the first mode, the display control unit 22 switches the display state of the signal display unit 30 via the I/F 71 based on a control signal received from the upper control device 200 by the communication unit 23. However, the method by which the display control unit 22 switches the display state of the signal display unit 30 in the first mode is not limited to this.

For example, in the first mode, the display control unit 22 may switch the display state of the signal display unit 30 based on the traffic volume detected by the detection unit 21. That is, in the first mode, the display control unit 22 may switch the display state of the signal display unit 30 based on the traffic volume detected by the detection unit 21, similarly to the case of the second mode.
In addition, in the first mode, the display control unit 22 may switch the display state of the signal display unit 30 based on a predetermined timing.

In the above explanation, the case where vehicles drive on the left side has been described, but the traffic light 100 according to this embodiment can also be applied when vehicles drive on the right side, just as when vehicles drive on the left side. When driving on the right side, the right turn described above for driving on the left side becomes a left turn. A right turn when driving on the left side, or a left turn when driving on the right side, as described above, means that the vehicle changes lanes by crossing the oncoming lane relative to the lane it was traveling in.

In this case, the above explanation that "the display control unit 22 switches the display state of the signal display unit 30 to give priority to right turns" means that "the control unit 20 (or the display control unit 22), based on the image captured by the imaging unit 10, switches the display state of the signal display unit 30 so as to give priority to the vehicle that is changing lanes when the vehicle changes lanes to intersect with the oncoming lane relative to the lane in which it has been traveling."

The above explanation that "the display control unit 22 switches the display state of the signal display unit 30 so as to adjust the time of the right-turn signal" means that "the control unit 20 (or the display control unit 22) switches the display state of the signal display unit 30 so as to adjust the time at which the vehicle that is changing lanes can proceed when the vehicle changes lanes to intersect with the oncoming lane relative to the lane that the vehicle has been traveling in, based on the image captured by the imaging unit 10."

In this way, the traffic light 100 according to this embodiment can make it easier for a vehicle to change course by crossing the oncoming lane of the lane in which it has been traveling, regardless of whether traffic is on the left or right side of the road. As a result, the traffic light 100 according to this embodiment can reduce (alleviate) congestion caused by a vehicle changing course by crossing the oncoming lane of the lane in which it has been traveling, regardless of whether traffic is on the left or right side of the road.

Note that if the traffic light 100 according to this embodiment is compatible with both left-hand traffic and right-hand traffic, the traffic light 100 may be configured to support either left-hand traffic or right-hand traffic when the traffic light 100 is powered on or when the traffic light 100 is shipped, via a setting unit included in the traffic light 100. Then, the control unit 20 may determine whether the traffic light 100 supports left-hand traffic or right-hand traffic based on this setting.

The traffic light 100 may also determine whether the lane in which the device controls traffic is for left-hand traffic or right-hand traffic based on the image captured by the imaging unit 10. Based on the result of this determination, the traffic light 100 may set in the device via a setting unit of the device whether the device is for left-hand traffic or right-hand traffic.

In the above explanation, the traffic light 100 has been described only as a traffic light for vehicles, but the traffic light 100 is not limited to vehicles, and may be a traffic light for people crossing a road (or a roadway) or a traffic light for trains on a railway.

In addition, each component of the signal control device 100 in FIG. 1, such as the detection unit 21, the display control unit 22, the communication unit 23, and the power supply switching unit 43, may be realized by dedicated hardware, or each component may be configured by a memory and a CPU (central processing unit), and the function of each component may be realized by loading a program for realizing the function into the memory and executing the program.

In addition, a program for realizing the functions of each of these components may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform processing by each of the components. Note that the term "computer system" here includes hardware such as the OS and peripheral devices.

Furthermore, if the WWW system is used, the "computer system" also includes the home page providing environment (or display environment).
In addition, "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" also includes those that dynamically hold a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and those that hold a program for a certain period of time, such as volatile memory inside a computer system that serves as a server or client in such cases. Furthermore, the above program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system.
As described above, according to the aspects of the present invention, even when a control signal for switching the display state of the signal display section cannot be received, the display state of the signal display section can be appropriately switched.

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes designs that do not deviate from the gist of the present invention.

10...imaging unit, 20...control unit, 21...detection unit, 22...display control unit, 30...signal display unit, 31...first light-emitting unit, 32...second light-emitting unit, 33...third light-emitting unit, 42...power storage unit, 50...sound collection unit

Claims (3)

A traffic light control device that controls a traffic light,
An imaging unit that captures an image of an area near an intersection;
an acquisition unit that wirelessly acquires information including time information indicating a time;
a display control unit that identifies a reference time based on the time information included in the information acquired by the acquisition unit, and switches a display state of a signal display unit attached to the traffic light based on the elapsed time from the identified reference time;
Equipped with
the display control unit adjusts a switching timing of the display state of the signal display unit based on the image captured by the imaging unit.
Traffic light control device. a power supply unit to which power is supplied from outside the device via a power line;
A power storage unit that stores power;
a power supply switching unit that switches a power supply for supplying power to each component of the device by selecting the power supply unit or the power storage unit;
a detection unit that detects a vehicle stopped near an intersection based on an image captured by the imaging unit;
Further comprising:
when the power supply switching unit selects the power storage unit, the display control unit specifies the reference time based on the time information included in the information acquired by the acquisition unit, and switches the display state based on the elapsed time from the specified reference time and a detection result by the detection unit.
The signal control device according to claim 1. The signal control device according to claim 1 or 2 is provided.
traffic light.

Images